Surfactants are a well known materials that possess an oil soluble and a water soluble group. The literature is full of surface active agents that have a fatty hydrophobe and a water soluble hydrophilic portion. Polysorbates are one class.
Wikiopedia defines polysorbate as an oily liquid. It is a class of emulsifiers used in some pharmaceuticals and food preparation. It is often used in cosmetics to solubilise essential oils into water based products. Polysorbates are derived from PEG-ylated sorbitan (a derivative of sorbitol) esterified with fatty acids. Surfactants that are esters of plain (non-PEG-ylated) sorbitan with fatty acids are usually referred to by the name Span.
U.S. Pat. No. 4,297,290 to Stockberger issued Oct. 27, 1981 teaches that sorbitan fatty acid esters can be prepared by forming anhydro sorbitol (a mixture of sorbitans, isosorbide, and unreacted sorbitol) by acid-catalyzed anhydrization, then reacting the resulting anhydro sorbitol with a fatty acid in the presence of a base at a temperature not exceeding about 215° C. Use of temperatures not over 215° C. results in products having substantially less color than those obtained at higher temperatures.
Polysorbates are emulsifiers, but are sticky on the hair and skin and do not provide appreciable softness, conditioning or antistatic properties.
U.S. Pat. No. 6,800,275 issued to O'Lenick, issued Oct. 5, 2007, incorporated herein by reference discloses “a series of polyester compounds made from the reaction of (a) a difunctional hydroxy compound, specifically polyoxyalkylene glycols, (b) a difunctional carboxylic acid, specifically dimer acid and hydrogenated dimer acid, and (c) a capping carboxylic acid, which only contains one acid group.” The patent teaches, “another critical component is the mono-functional carboxylic group, which caps the polymer and provides terminal oil soluble portion to the molecule. This lowers the critical micelle concentration and provides improved skin deposition”.
We have surprisingly found that contrary to the teachings of U.S. Pat. No. 6,800,275, the use of a polysorbate, and dimer acid without the required capping fatty acid offers improved lubricity and skin feel.